US patent publication 2005/0173395 describes a plug-in connector for a glow plug of a diesel engine. This plug-in connector is shaped to fit on a glow plug of a diesel engine, where both sides of the connection have several electrical contact areas which can be brought together. These contact areas form a connection for feeding power to the glow plug for firing the diesel engine and also form a connection for at least one sensor inside the glow plug. The sensor signals parameters, e.g. pressure or temperature, detected at the glow plug and transmits them for evaluation to n on-board computer that controls the diesel engine.
Providing such a plug-in connector for a glow plug with a sensor has the advantage that the installation is very compact, so that the unit consisting of plug-in connector, glow plug and sensor requires little space in or on the diesel engine. The detection of parameters in the area of the glow plug has the further advantage that combustion inside the diesel engine can be substantially better controlled or regulated, and exhaust emissions, noise, and the like of the diesel engine can be reduced to comply with today's especially strict environmental regulations. For this case it is especially important that the sensor signals from the glow plug be transmitted via the plug-in connector to the downstream controller.
Such a connector is subject to extremely high stress, especially with regard to temperature and vibrations in the area of the diesel engine, especially when used in a vehicle. Here, temperature variations of −40° C. to +150° C. are not unheard of. Further adverse conditions such as moisture, splashing water, dirt particles and the like are also a problem. Hence, it is of special importance that the plug-in connector on the one hand can be quickly and easily fitted toto the glow plug, to which end the plug-in connector is designed with a circular hole. On the other hand it is essential that the plug-in connector be fitted to the glow plug in a correct position to contact the several contact areas between plug-in connector and glow plug electrically with each other. Finally, it is critical that, once the plug-in connector has been fitted toto the glow plug in the correct position, this plug-in connector withstands the described environmental conditions and does not come loose from the glow plug.